U.S. Pat. No. 3,744,749, which is assigned to the same corporate entity to which the present invention is assigned, describes and shows a ram-type BOP where a ram sealing member 41 formed of rubber is held between metal retainer plates 42 for preventing extrusion of the rubber when it is in the sealing or closed position. A top seal 44 is formed integral with sealing member 41 as shown in FIG. 2. U.S. Pat. No. 3,647,174 teaches a similar integrally-formed top and front BOP seal 15. U.S. Pat. No. 3,791,616 shows a ram-type BOP with a front packer seal 16 located between rigid retainer plates 16a and 16b and a top seal element 17.
Other types of seals for ram-type BOP's are shown and described in the Composite Catalog of Oilfield Equipment and Services, 1976-1977 (vol. 2), p. 3303 where a ram-type BOP for the Hydril Company, which owns the present invention, is shown in detail. The front packer and top seals are formed as separate elements and are removably mounted in grooves formed in the BOP ram. The elements can be removed and replaced when worn. Other seals formed of rubber with fiber or polyurethane replacable inserts have also been used.